'discovery->data.info' length is 22, NICKNAME_MAX_LEN is 21, so the
strncpy() will always left the last byte of 'discovery->data.info'
uninitialized.

When 'text' length is longer than 21 (NICKNAME_MAX_LEN), if still left
the last byte of 'discovery->data.info' uninitialized, the next
strlen() will cause issue.

Also 'discovery->data' is 'struct irda_device_info' which defined in
"include/uapi/...", it may copy to user mode, so need whole initialized.

All together, need use kzalloc() instead of kmalloc() to initialize all
members firstly.
Signed-off-by: NChen Gang <gang.chen@asianux.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The net/netlabel/netlabel_domainhash.c:netlbl_domhsh_add() function
does not properly validate new domain hash entries resulting in
potential problems when an administrator attempts to add an invalid
entry.  One such problem, as reported by Vlad Halilov, is a kernel
BUG (found in netlabel_domainhash.c:netlbl_domhsh_audit_add()) when
adding an IPv6 outbound mapping with a CIPSO configuration.

This patch corrects this problem by adding the necessary validation
code to netlbl_domhsh_add() via the newly created
netlbl_domhsh_validate() function.

Ideally this patch should also be pushed to the currently active
-stable trees.
Reported-by: NVlad Halilov <vlad.halilov@gmail.com>
Signed-off-by: NPaul Moore <pmoore@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

commit 0178b695 ("ipv6: Copy cork options in ip6_append_data")
added some code duplication and bad error recovery, leading to potential
crash in ip6_cork_release() as kfree() could be called with garbage.

use kzalloc() to make sure this wont happen.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Cc: Neal Cardwell <ncardwell@google.com>

rcu_barrier() only waits for the currently scheduled rcu functions
to finish - it won't wait for any function scheduled via another
call_rcu() within an rcu scheduled function.

Unfortunately our batadv_tt_orig_list_entry_free_ref() does just that,
via a batadv_orig_node_free_ref() call, leading to our rcu_barrier()
call potentially missing such a batadv_orig_node_free_ref().

This patch fixes this issue by calling the batadv_orig_node_free_rcu()
directly from the rcu callback, removing the unnecessary, additional
call_rcu() layer here.
Signed-off-by: NLinus Lüssing <linus.luessing@web.de>
Signed-off-by: NMarek Lindner <lindner_marek@yahoo.de>
Acked-by: NAntonio Quartulli <ordex@autistici.org>

GSO TCP handler has following issues :

1) ooo_okay from original GSO packet is duplicated to all segments
2) segments (but the last one) are orphaned, so transmit path can not
get transmit queue number from the socket. This happens if GSO
segmentation is done before stacked device for example.

Result is we can send packets from a given TCP flow to different TX
queues (if using multiqueue NICS). This generates OOO problems and
spurious SACK & retransmits.

Fix this by keeping socket pointer set for all segments.

This means that every segment must also have a destructor, and the
original gso skb truesize must be split on all segments, to keep
precise sk->sk_wmem_alloc accounting.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Maciej Żenczykowski <maze@google.com>
Cc: Tom Herbert <therbert@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This target assumes that tcph->doff is well-formed, that may be well
not the case. Add extra sanity checkings to avoid possible crash due
to read/write out of the real packet boundary. After this patch, the
default action on malformed TCP packets is to drop them. Moreover,
fragments are skipped.
Reported-by: NRafal Kupka <rkupka@telemetry.com>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Since (69b34fb9 netfilter: xt_LOG: add net namespace support
for xt_LOG), we hit this:

[ 4224.708977] BUG: unable to handle kernel NULL pointer dereference at 0000000000000388
[ 4224.709074] IP: [<ffffffff8147f699>] ipt_log_packet+0x29/0x270

when callling log functions from conntrack both in and out
are NULL i.e. the net pointer is invalid.

Adding struct net *net in call to nf_logfn() will secure that
there always is a vaild net ptr.

Reported as netfilter's bugzilla bug 818:
https://bugzilla.netfilter.org/show_bug.cgi?id=818Reported-by: NRonald <ronald645@gmail.com>
Signed-off-by: NHans Schillstrom <hans@schillstrom.com>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

commit fb745e9a ("net/802/mrp: fix possible race condition when
calling mrp_pdu_queue()") introduced a lockdep splat.

[   19.735147] =================================
[   19.735235] [ INFO: inconsistent lock state ]
[   19.735324] 3.9.2-build-0063 #4 Not tainted
[   19.735412] ---------------------------------
[   19.735500] inconsistent {IN-SOFTIRQ-W} -> {SOFTIRQ-ON-W} usage.
[   19.735592] rmmod/1840 [HC0[0]:SC0[0]:HE1:SE1] takes:
[   19.735682]  (&(&app->lock)->rlock#2){+.?...}, at: [<f862bb5b>]
mrp_uninit_applicant+0x69/0xba [mrp]

app->lock is normally taken under softirq context, so disable BH to
avoid the splat.
Reported-by: NDenys Fedoryshchenko <denys@visp.net.lb>
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: David Ward <david.ward@ll.mit.edu>
Cc: Cong Wang <amwang@redhat.com>
Tested-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

TCP md5 communications fail [1] for some devices, because sg/crypto code
assume page offsets are below PAGE_SIZE.

This was discovered using mlx4 driver [2], but I suspect loopback
might trigger the same bug now we use order-3 pages in tcp_sendmsg()

[1] Failure is giving following messages.

huh, entered softirq 3 NET_RX ffffffff806ad230 preempt_count 00000100,
exited with 00000101?

[2] mlx4 driver uses order-2 pages to allocate RX frags
Reported-by: NMatt Schnall <mischnal@google.com>
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Bernhard Beck <bbeck@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

We forget to call dev_put() on error path in xfrm6_fill_dst(),
its caller doesn't handle this.

Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: NCong Wang <amwang@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

There is a hole in struct ip6_tnl_parm2, so we have to
zero the struct on stack before copying it to user-space.

Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: NCong Wang <amwang@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

We have seen multiple NULL dereferences in __inet6_lookup_established()

After analysis, I found that inet6_sk() could be NULL while the
check for sk_family == AF_INET6 was true.

Bug was added in linux-2.6.29 when RCU lookups were introduced in UDP
and TCP stacks.

Once an IPv6 socket, using SLAB_DESTROY_BY_RCU is inserted in a hash
table, we no longer can clear pinet6 field.

This patch extends logic used in commit fcbdf09d
("net: fix nulls list corruptions in sk_prot_alloc")

TCP/UDP/UDPLite IPv6 protocols provide their own .clear_sk() method
to make sure we do not clear pinet6 field.

At socket clone phase, we do not really care, as cloning the parent (non
NULL) pinet6 is not adding a fatal race.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

EXPORT_SYMBOL and inline directives are contradictory to each other.
The patch fixes this inconsistency.

Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: NDenis Efremov <yefremov.denis@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

nc_worker accesses the originator table during its periodic
work, but since the originator table is freed before
stopping the worker this leads to a global protection fault.

Fix this by killing the worker (in nc_free) before freeing
the originator table.

Moreover tidy up the entire clean up routine by running all
the subcomponents freeing procedures first and then killing
the TT and the originator tables at the end.
Signed-off-by: NAntonio Quartulli <ordex@autistici.org>
Signed-off-by: NMarek Lindner <lindner_marek@yahoo.de>

In the outgoing ARP request snooping routine in DAT, ARP
Request sent by local clients which are supposed to be
replied by other local clients can be silently dropped.

The destination host will reply by itself through the LAN
and therefore there is no need to involve DAT.
Reported-by: NCarlos Quijano <carlos@crqgestion.es>
Signed-off-by: NAntonio Quartulli <ordex@autistici.org>
Tested-by: NCarlos Quijano <carlos@crqgestion.es>
Signed-off-by: NMarek Lindner <lindner_marek@yahoo.de>

Reported-by: NSven Eckelmann <sven@narfation.org>
Signed-off-by: NMarek Lindner <lindner_marek@yahoo.de>
Acked-by: NMartin Hundebøll <martin@hundeboll.net>
Signed-off-by: NAntonio Quartulli <ordex@autistici.org>

batadv_param_set_ra() strips the trailing '\n' from the supplied
string buffer without checking the length of the buffer first. This
patches avoids random memory access and associated potential
crashes.
Reported-by: NSasha Levin <sasha.levin@oracle.com>
Signed-off-by: NMarek Lindner <lindner_marek@yahoo.de>
Signed-off-by: NAntonio Quartulli <ordex@autistici.org>

Rather than having logic to calculate inner protocol in every
tunnel gso handler move it to gso code. This simplifies code.

Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Cong Wang <amwang@redhat.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: NPravin B Shelar <pshelar@nicira.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The current code works, but sort of by accident: it obviously didn't
intend the error return to be interpreted as "true".
Reported-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

The worry here is that fragm_sz could be zero since it comes from
skb->data.
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The bearer_id here comes from skb->data and it can be a number from 0 to
7.  The problem is that the ->links[] array has only 2 elements so I
have added a range check.
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The return value is reversed from mutex_trylock().
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The same story as with fib_trie patch - vfree() from RCU callbacks
is legitimate now.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Now that vfree() can be called from interrupt contexts, there's no
need to play games with schedule_work() to escape calling vfree()
from RCU callbacks.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch fixes race between inet_frag_lru_move() and inet_frag_lru_add()
which was introduced in commit 3ef0eb0d
("net: frag, move LRU list maintenance outside of rwlock")

One cpu already added new fragment queue into hash but not into LRU.
Other cpu found it in hash and tries to move it to the end of LRU.
This leads to NULL pointer dereference inside of list_move_tail().

Another possible race condition is between inet_frag_lru_move() and
inet_frag_lru_del(): move can happens after deletion.

This patch initializes LRU list head before adding fragment into hash and
inet_frag_lru_move() doesn't touches it if it's empty.

I saw this kernel oops two times in a couple of days.

[119482.128853] BUG: unable to handle kernel NULL pointer dereference at           (null)
[119482.132693] IP: [<ffffffff812ede89>] __list_del_entry+0x29/0xd0
[119482.136456] PGD 2148f6067 PUD 215ab9067 PMD 0
[119482.140221] Oops: 0000 [#1] SMP
[119482.144008] Modules linked in: vfat msdos fat 8021q fuse nfsd auth_rpcgss nfs_acl nfs lockd sunrpc ppp_async ppp_generic bridge slhc stp llc w83627ehf hwmon_vid snd_hda_codec_hdmi snd_hda_codec_realtek kvm_amd k10temp kvm snd_hda_intel snd_hda_codec edac_core radeon snd_hwdep ath9k snd_pcm ath9k_common snd_page_alloc ath9k_hw snd_timer snd soundcore drm_kms_helper ath ttm r8169 mii
[119482.152692] CPU 3
[119482.152721] Pid: 20, comm: ksoftirqd/3 Not tainted 3.9.0-zurg-00001-g9f95269 #132 To Be Filled By O.E.M. To Be Filled By O.E.M./RS880D
[119482.161478] RIP: 0010:[<ffffffff812ede89>]  [<ffffffff812ede89>] __list_del_entry+0x29/0xd0
[119482.166004] RSP: 0018:ffff880216d5db58  EFLAGS: 00010207
[119482.170568] RAX: 0000000000000000 RBX: ffff88020882b9c0 RCX: dead000000200200
[119482.175189] RDX: 0000000000000000 RSI: 0000000000000880 RDI: ffff88020882ba00
[119482.179860] RBP: ffff880216d5db58 R08: ffffffff8155c7f0 R09: 0000000000000014
[119482.184570] R10: 0000000000000000 R11: 0000000000000000 R12: ffff88020882ba00
[119482.189337] R13: ffffffff81c8d780 R14: ffff880204357f00 R15: 00000000000005a0
[119482.194140] FS:  00007f58124dc700(0000) GS:ffff88021fcc0000(0000) knlGS:0000000000000000
[119482.198928] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[119482.203711] CR2: 0000000000000000 CR3: 00000002155f0000 CR4: 00000000000007e0
[119482.208533] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[119482.213371] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[119482.218221] Process ksoftirqd/3 (pid: 20, threadinfo ffff880216d5c000, task ffff880216d3a9a0)
[119482.223113] Stack:
[119482.228004]  ffff880216d5dbd8 ffffffff8155dcda 0000000000000000 ffff000200000001
[119482.233038]  ffff8802153c1f00 ffff880000289440 ffff880200000014 ffff88007bc72000
[119482.238083]  00000000000079d5 ffff88007bc72f44 ffffffff00000002 ffff880204357f00
[119482.243090] Call Trace:
[119482.248009]  [<ffffffff8155dcda>] ip_defrag+0x8fa/0xd10
[119482.252921]  [<ffffffff815a8013>] ipv4_conntrack_defrag+0x83/0xe0
[119482.257803]  [<ffffffff8154485b>] nf_iterate+0x8b/0xa0
[119482.262658]  [<ffffffff8155c7f0>] ? inet_del_offload+0x40/0x40
[119482.267527]  [<ffffffff815448e4>] nf_hook_slow+0x74/0x130
[119482.272412]  [<ffffffff8155c7f0>] ? inet_del_offload+0x40/0x40
[119482.277302]  [<ffffffff8155d068>] ip_rcv+0x268/0x320
[119482.282147]  [<ffffffff81519992>] __netif_receive_skb_core+0x612/0x7e0
[119482.286998]  [<ffffffff81519b78>] __netif_receive_skb+0x18/0x60
[119482.291826]  [<ffffffff8151a650>] process_backlog+0xa0/0x160
[119482.296648]  [<ffffffff81519f29>] net_rx_action+0x139/0x220
[119482.301403]  [<ffffffff81053707>] __do_softirq+0xe7/0x220
[119482.306103]  [<ffffffff81053868>] run_ksoftirqd+0x28/0x40
[119482.310809]  [<ffffffff81074f5f>] smpboot_thread_fn+0xff/0x1a0
[119482.315515]  [<ffffffff81074e60>] ? lg_local_lock_cpu+0x40/0x40
[119482.320219]  [<ffffffff8106d870>] kthread+0xc0/0xd0
[119482.324858]  [<ffffffff8106d7b0>] ? insert_kthread_work+0x40/0x40
[119482.329460]  [<ffffffff816c32dc>] ret_from_fork+0x7c/0xb0
[119482.334057]  [<ffffffff8106d7b0>] ? insert_kthread_work+0x40/0x40
[119482.338661] Code: 00 00 55 48 8b 17 48 b9 00 01 10 00 00 00 ad de 48 8b 47 08 48 89 e5 48 39 ca 74 29 48 b9 00 02 20 00 00 00 ad de 48 39 c8 74 7a <4c> 8b 00 4c 39 c7 75 53 4c 8b 42 08 4c 39 c7 75 2b 48 89 42 08
[119482.343787] RIP  [<ffffffff812ede89>] __list_del_entry+0x29/0xd0
[119482.348675]  RSP <ffff880216d5db58>
[119482.353493] CR2: 0000000000000000

Oops happened on this path:
ip_defrag() -> ip_frag_queue() -> inet_frag_lru_move() -> list_move_tail() -> __list_del_entry()
Signed-off-by: NKonstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Florian Westphal <fw@strlen.de>
Cc: Eric Dumazet <edumazet@google.com>
Cc: David S. Miller <davem@davemloft.net>
Acked-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/sunrpc/auth_gss/gss_rpc_xdr.c: In function ‘gssx_dec_option_array’:
net/sunrpc/auth_gss/gss_rpc_xdr.c:258: warning: ‘creds’ may be used uninitialized in this function

Return early if count is zero, to make it clearer to the compiler (and the
casual reviewer) that no more processing is done.
Signed-off-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

This patch fixes the following compilation error:

net/netfilter/nf_log.c:373:38: error: 'struct netns_nf' has no member named 'proc_netfilter'

if procfs is not set.

The netns support for nf_log, nfnetlink_log and nfnetlink_queue_core
requires CONFIG_PROC_FS in the removal path of their respective
/proc interface since net->nf.proc_netfilter is undefined in that
case.
Reported-by: NFengguang Wu <fengguang.wu@intel.com>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>
Acked-by: NGao feng <gaofeng@cn.fujitsu.com>

TCP metric cache expires entries after one hour.

This probably make sense for TCP RTT/RTTVAR/CWND, but not
for TCP fastopen cookies.

Its better to try previous cookie. If it appears to be obsolete,
server will send us new cookie anyway.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Jakub reported that it is fairly easy to trigger the BUG() macro
from user space with TPACKET_V3's RX_RING by just giving a wrong
header status flag. We already had a similar situation in commit
7f5c3e3a (``af_packet: remove BUG statement in
tpacket_destruct_skb'') where this was the case in the TX_RING
side that could be triggered from user space. So really, don't use
BUG() or BUG_ON() unless there's really no way out, and i.e.
don't use it for consistency checking when there's user space
involved, no excuses, especially not if you're slapping the user
with WARN + dump_stack + BUG all at once. The two functions are
of concern:

  prb_retire_current_block() [when block status != TP_STATUS_KERNEL]
  prb_open_block() [when block_status != TP_STATUS_KERNEL]

Calls to prb_open_block() are guarded by ealier checks if block_status
is really TP_STATUS_KERNEL (racy!), but the first one BUG() is easily
triggable from user space. System behaves still stable after they are
removed. Also remove that yoda condition entirely, since it's already
guarded.
Reported-by: NJakub Zawadzki <darkjames-ws@darkjames.pl>
Signed-off-by: NDaniel Borkmann <dborkman@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch set correct skb->protocol so that inner packet can
lookup correct gso handler.
Signed-off-by: NPravin B Shelar <pshelar@nicira.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

For ipv6 traffic, GRE can generate packet with strange GSO
bits, e.g. ipv4 packet with SKB_GSO_TCPV6 flag set.  Therefore
following patch relaxes check in inet gso handler to allow
such packet for segmentation.
This patch also fixes wrong skb->protocol set that was done in
gre_gso_segment() handler.
Reported-by: NSteinar H. Gunderson <sesse@google.com>
CC: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NPravin B Shelar <pshelar@nicira.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

A bridge should only send topology change notice if it is not
the root bridge. It is possible for message age timer to elect itself
as a new root bridge, and still have a topology change timer running
but waiting for bridge lock on other CPU.

Solve the race by checking if we are root bridge before continuing.
This was the root cause of the cases where br_send_tcn_bpdu would OOPS.
Reported-by: NJerryKang <jerry.kang@samsung.com>
Signed-off-by: NStephen Hemminger <stephen@networkplumber.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When sending packets, TIPC bearers use skb_clone() before writing their
hardware header. This will however NOT copy the data buffer.
So when the same packet is sent over multiple bearers (to reach multiple
nodes), the same socket buffer data will be treated by multiple
tipc_media drivers which will write their own hardware header through
dev_hard_header().
Most of the time this is not a problem, because by the time the
packet is processed by the second media, it has already been sent over
the first one. However, when the first transmission is delayed (e.g.
because of insufficient bandwidth or through a shaper), the next bearer
will overwrite the hardware header, resulting in the packet being sent:
a) with the wrong source address, when bearers of the same type,
e.g. ethernet, are involved
b) with a completely corrupt header, or even dropped, when bearers of
different types are involved.

So when the same socket buffer is to be sent multiple times, send a
pskb_copy() instead (from the second instance on), and release it
afterwards (the bearer will skb_clone() it anyway).
Signed-off-by: NGerlando Falauto <gerlando.falauto@keymile.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NGerlando Falauto <gerlando.falauto@keymile.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NGerlando Falauto <gerlando.falauto@keymile.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Just convert those messages to dprintk()s so that they can be used
when debugging.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Signed-off-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NPatrick McHardy <kaber@trash.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Create a slab cache to manage allocation of ceph_osdc_request
structures.

This resolves:
    http://tracker.ceph.com/issues/3926Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>

Create a slab cache to manage ceph_msg_data structure allocation.

This is part of:
    http://tracker.ceph.com/issues/3926Signed-off-by: NAlex Elder <elder@inktank.com>
Reviewed-by: NJosh Durgin <josh.durgin@inktank.com>